Pilot design, channel estimation, and target detection for integrated sensing and communication with OTFS

Recent studies shows that the orthogonal time frequency space (OTFS) waveform is a promising candidate for future communication. To meet users' potential demand for Integrated Sensing and Communication (ISAC) applications in 6G, the usage of OTFS for both radar sensing and wireless communication needs to be explored. In this paper, we propose a Fast Algorithm OTFS radar (FAOR) that can perform radar sensing in low complexity to detect the range and speed of the targets. It computes the 2D cyclic correlation of transmitted signal with the reordered delay Doppler (DD) domain received signals, and then generates the 2D range-Doppler map. It can be applied not only to monostatic radar but also to bistatic radar with a much lower computational complexity compared to state-of-the-art radar sensing technology. With the detected time delays and Doppler frequencies of the targets after the radar sensing, we propose a pilot-aided channel estimation method. The multifunction pilot symbol can serve the purpose of both bistatic radar sensing and channel estimation without any guard symbol added, while reducing the peak-to-average power ratio (PAPR) considerably compared to the conventional pilot design. The simulation results show that the proposed scheme outperforms the compared algorithms and gives decent performance in both radar sensing and channel estimation.